Adjustable feed mechanism for sewing machines



ADJUSTABLE FEED MECHANISM FOR SEWING MACEINES Filed sept. 28, 1949 Dec. 4, 1951 R. L.. HOFFMEISTER 5 sheets-sheet 1 R. L. HOFFM EISTER ADJUSTABLE FEED MECHANISM FOR SEWING MACHINES Dec. 4, Y1951 5 Sheets-Sheet 2 Filed Sept. 28, 1949 @a W A@ @a www ADJUSTABLE FEED MECHANISM EOE SEWING MACHINES Filed sept. 28, 1949 Dec 4, 1951 R. L. HoFFMr-:ISTER 5 Sheets-Sheet 5 Patented Dec. 4, 1951 Robert L. Hoffmeister, WestflellLN. -Jf.,vass'gnor to The Singer Manufacturing Company, SElizabeth, N. J., a corporation `of New Jersey Application September 2:8, 1949, Serial o.118,"33*7 (Cl. i12-210) 7 Claims.

This invention relates to sewing machines and more particularly to a work fee-ding mechanism therefor, in which a feed-actuating eccentric may be `adjusted to vary its eccentricity and thereby to change the length of the stitches.

The invention has foran object to provide a mechanism for adjusting the stitch-length while the machine is .in operation,'the stitch-length adjustment being accomplished by means of a regulating lever disposed .at the front of the sewing machine in a location particularly convenient to the operator.

Another object of the present invention is to provide an adjustable `feed mechanism for a sewing machine in which the feed actuating eccentrics are located within a closed lubrication compartment and the devices for regulating the eccentricity of the feed-advance eccentric have substantially oil-tight connections with the wall of'said lubrication compartment.

Still another object of the invention is to provide a feed regulating mechanism which is of a positive and preferably self-irreversible nature Y so that the eccentric for any position of adjustment is positively held at the desired eccentricity, from which .it cannot move under centrifugal force or by the forces of reaction to which the eccentric may be subjected at vhigh operative speeds.

With the `above and more specic objects in view, the invention comprises the devices, combinations, `and arrangements of parts hereinafter described in connection with the accompanying drawings from which the several features of the invention land the advantages Aattained thereby will be readily understood by those skilled in the art.

In the drawings: Y

Fig. 1 is a longitudinal vertical sectional view of a machine having my invention embodied therein. v

Fig. 2 is a transverse vertical sectional view taken substantially along the line 2--2, Fig. l.

Fig. 3 is a sectional view taken substantially along the line 3-3, Fig. 1, showing the details of construction of the hand-operated regulating means Vfor adjusting the eccentricity of the feedactuating eccentric.

Fig. 4 is a longitudinal vertical sectional view taken substantially along the axis of the armshaft with the feed eccentrics in section to show their details of construction and the lubrication conducting ports used to supply lubricant to the bearing surfaces.

Fig. 5 is a horizontal sectional view taken substantially along the line 5 5, Fig. 1. n

Fig. 6 is a vertical sectional view taken through the axis of the arm-shaft, showing the feed-advance eccentric shifted to a position of substantially zero eccentricity.

Referring to the drawings, the present irnprovement has been embodied in a sewing ma- Y '2 chine Vincluding a frame comprising a bed ID, from one end of which rises the hollow standard |I of a tubularbracket-arm I2 overhanging the bed and terminating at its free end in a hollow head I3. Journaled in the bracket-arm I2 for rotary movement .is lan arm-shaft VIll having a pulley I5 iixed to one of its ends. To the other end of /the shaft |4- there is secured a crank l5 which actuates, through a link li, a needle-bar i8 which is journaled in bearings in the head I3 and to which is attached a thread-carrying needle l il` Cooperating with the needle i3 in the formation of lock-stitches is a loop-taker 2l), of the conventional rotary hook type. The rotary hook 20 is carried by one end of a rotary bedshaft 2| (Fig. l) connected at its other end by gearing 22 and 23 to a vertical shaft l2t. The vertical shaft 24 is connected by gearing 25 `and 26 Vto the arm-shaft I4.

The work to be stitched is adapted to be fed past the stitch-forming devices by means of a feed-dog 21 against which the Work is yieldingly held by the usual spring-biased presser-foot 28. As will be observed in Fig. 2, the feed-dog 21 is mounted on a feed-bar 29 pivotallyconnected at one end to the usual feed-advance rocher 3i) carried by the outer end-portion of a feed-ad- Vance and -return rock-shaft 3|'. At its other end., the feed-bar 29 is forked as at 32 to embrace a slide-block 33 pivoted to one end of a feedlift rocker 34 clamped upon the :front end-portion of a feed-lift rock-shaft 35.

The two rock-shafts 3| and 35 are actuated from the rotary arm-shaft I4 by means of sepa-- rate eccentric's 36 and 31. The eccentric 36 is the feed-advance eccentric andis constructed so that its eccentricity can be adjusted to Vary the stitchlength, while the eccentric 31 is the feed-lift eccentric and, preferably, it is vdesigned to have a fixed eccentricity. The feed-lift eccentric 31 is preferably cut into the hub of the gear 23 and is embraced by the upper end of a pitman 33 which is pivoted at its lower end to the extremity of a rock-arm 33 preferably integral with the feed-lift rockshaft 35. The adjustable eccentric 36 is embraced by the upper end of a pitman 4) having 4its lower end pivoted to the free end of a rocker 41 which is preferably clamped on the feed-advance rock-shaft 3|. Actuation of the rotary armshaft |11 will impart to the feed-advance and feed-lift rock-shafts 3| and 35 oscillations which transmit a conventional four-motion travel to the feed-dog 2l. The amount ci lift imparted to the feed-dog 2l is fixed since the eccentricity of the feedlif`t eccentric 37 is not adjustable. Change in the length of stitch is effected by changing the eccentricity of the feedadvance eccentric 36 and this invention pertains particularly to the details of thefadjustable eccentric and the means employed yfor regulating the eccentricity of the eccentric.

,y Referring now to Figs. 4 and 6, it will be seen that the feed-advance eccentric 36 is composed of two parts, the outer part 42 and the inner part 43. These two parts, of which one is disposed wholly within the other, have splined cylindrical engaging surfaces 44 on an axis inclined to the longitudinal axis of the arm-shaft I4. The outer part 42 of the eccentric is fixed for rotation with the arm-shaft I4, see Figs. 4 and 5, by engagement of a radial projection 45 on the outer part 42 of the eccentric with a slot 46 in a collar 41 fixed on the shaft I4 by a set screw 48. The outer part 42 of the eccentric `36 is constrained against movement longitudinally of the shaft I4 by the feed-lift eccentric 31 which is fixed on the shaft I4, the feed-lift eccentric abutting against the outer face of a thrust-cap 49 secured on the outer part 42 by a set screw 56. From the above, it will be understood that the outer part 42 of the eccentric is conned against movement longitudinally of the arm-shaft I4 by the collar 41 on one side and the gear 26 on the other side, and that it is free to shift radially of the armshaft I4 in a line determined by the slot 46 in the collar 41.

The outer part 42 of the eccentric 36 is adapted to be shifted radially of the arm-shaft I4 to effect a change in the eccentricity of the eccenof the arm-shaft. To move the inner part 43 lengthwise of the arm-shaft, the inner part has threaded into it a diameter pin 5I extending through alined slots 52 formed in the hollow armtric, by movement of the inner part 43 lengthwise v shaft I4. Connected at the midpoint of the dithrough alined slots 56 in the arm-shaft I4 and threaded into a sliding sleeve'51 journaled on the arm-shaft I4, which sliding sleeve is adapted to rotate with said arm-shaft. The sliding sleeve 51 is flanged, as at 58 and 58, to define between said flanges an annular groove 6i] in which is disposed an inverted U-shaped shoe 6i (Figs. 3 and 5) pivotally supported on a pair of fulcrumpins 62 and -63 secured in the depending limbs 64 and 65 of a yoke 66. The yoke 66 is pivotally hung on a supporting pin 61 pressed into a coverplate 68 detachably secured to the bracket-arm I2 by the screws 69. The yoke 66 is forcibly swung about its supporting pin 61 into selected positions by manually controlled means including a cam or eccentric 16 (Figs. 3 and 5) which fits into a slot 1I formed in the limb 65 of the yoke 66. The eccentric 10 is carried by a shaft 12 which is journaled in a shouldered bushing 13 mounted in the front wall of the bracket-arm I2. Secured on the exposed end of the shaft 12 is a knob 14 which is adapted to be grasped by the operator and turned to effect a change in the stitch-length; To preclude accidental turning of the eccentric 10 a spring-washer 15 is interposed between the knob 14 and the face of the shouldered bushing 13, whereby the eccentric 10 is frictionally held in set position. To assist in obtaining the proper setting of the knob 14, there is scribed preferably on a flange 14 on the knob 14 indicia which cooperate with a fixed pointer 16 (Fig. 5) secured beneath the shoulder of the bushing 13.

' From the above description, it will be understood that when it is desired to regulate the length of the stitch, the knob 14 may be turned, either while the machine is in operation or when the machine is stopped. Turning of the knob 14 turns the eccentric 10 which swings the yoke 66 about its supporting fulcrum 61.

The movement of the yoke 66, through the shoe 6|, transmits to the sleeve 51 sliding movement endwise of the arm-shaft I4. The sleeve 5l', through the shiftrod 53, moves the inner part 43 of the eccentric 36 relative to the outer part 42. Because of the inclination of the splined cylindrical engaging surfaces 44 of the inner and outer parts of the eccentric 36, movement of the inner part 43 relative to the outer part 42, results in the outer part moving radially of the arm-shaft I4 along a line determined by the groove 46 in the collar 41. Thus, the eccentricity of the eccentric 36 is changed. In the present case, the parts in the position shown in Fig. 4 illustrate the eccentric 36 in maximum eccentricity, while in Fig. 6, the parts are shown in substantially zero eccentricity. It will be appreciated that the inner and outer parts of the eccentric 36 can be proportioned so that in moving from one extreme position to the other extreme position the eccentricity of the eccentric shifts from a maximum on one side of the axis of the arm-shaft to a maximum on the other side of said axis, and in whichr case the feed shifts from maximum forward feed to maximum reverse feed. It will be further understood that a suitably shaped cam can be substituted for the eccentric 16 and when this is done the scale on the flange 14 of the knob 14 can be linear.

The present adjustable feed mechanism is shown as applied to a high speed sewing machine of the type having a lubricating system similar to that disclosed in the U. S. patent of R. Kaier, No. 2,206,285, issued July 2, 1940. In the present drawings, oil under pressure is elevated from a sump beneath the bed I6 by a centrifugal pump 'I1 (Fig. l) through a conduit 18 which is connected to a bearing-lug 19 for the arm-shaft I4. The oil delivered to the bearing lug 19 is conducted through the radial duct 86 (Fig. l) into the bore 54 of the arm-shaft I4. Someof theoil f in the bore flows outwardly through the alined slots 52 (Figs. 4 and 6) and into the cavity defined by the splined bore of the outer part 42 of the eccentric 35. Centrifugal force causes some of the ol in the cavity of the outer part 42 to travel through the ducts 8|, 62 and 83 to the eccentric face 36 when the eccentric parts 42 and 43 are in the position shown in Fig. 4. When the eccentric parts 42 and 43 are in the position shown in Fig. 6, some of the oil in the cavity of the outer part 42 ows outwardly through the ducts 64, 65 and 86 to the eccentric face 36.

Since one end of the duct 85 is opened, oil is also led into the groove 46 in the collar 41 to lubricate the engaging surfaces of the projection 45. It will be understood that the eccentrics 36 and 31 are located within a substantially closed lubrication compartment and that the excess oil from the eccentrics is returned to the sump at the bottom of the compartment. The shaft'engagingv bore of the sliding sleeve 51 is lubricated by oil from the bore 54 of the arm-shaft I4 which is 'transmitted through the slots 56 in the armshaft.

It will be understood that the design of the eccentric adjusting connections is such that no positive locking means is required to maintain the inner element 43 of the eccentric 36 in .set position. The connections are self-'irreversible to the extent that centrifugal force or the forces of reaction set up by high speed operation of the eccentric do not effect an accidental shift of the inner element 43 of the eccentric. The advantage of this construction is that the stitchlength can be changed without rst having to release any locking device.

Having thus .set forth the nature of the invention, what I claim herein is:

1. A work-feeding mechanism for sewing machines having a rotary shaft, comprising a movable feed-dog, a feed-lift eccentric operatively connected to said feed-dog, an adjustable feedadvance eccentric mounted on said rotary shaft and operatively connected to said feed-dog and includingrelatively movable inner and outer elements having interengaging surfaces inclined to the longitudinal axis of said rotary shaft, a sleeve slidable on said rotary shaft, a connection between said sleeve and one of the elements of said feed-advance eccentric, an eccentric operatively associated with said sleeve, and means providing for turning said eccentric and thereby shifting said sleeve lengthwise of said rotary shaft.

2. A work-feeding mechanism for sewing machines having a rotary shaft, comprising a movable feed-dog, a feed-lift eccentric operatively connected to said feed-dog, an adjustable feedadvance eccentric mounted on said rotary shaft and operatively connected to said feed-dog and including relatively movable inner and outer elements having interengaging surfaces inclined to the longitudinal axis of said rotary shaft, a sleeve slidable on said rotary shaft, a connection between said sleeve and one of the elements of said feed-advance eccentric, a pivotally mounted yoke straddling said sleeve and connected thereto to permit rotation of said sleeve relative to said yoke, and manually turnable means connected to said yoke providing for swinging said yoke about its pivot.

3. A work-feeding mechanism for sewing machines having a rotary shaft formed with an axial bore, comprising a movable feed-dog, a feed-lift eccentric operativelyconnected to said feed-dog, an adjustable feed-advance eccentric mounted on said rotary shaft and operatively connected to said feed-dog and including relatively movable inner and outer elements having interengaging surfaces inclined to the longitudinal axis of said rotary shaft, a sleeve slidable on said rotary shaft, a shift-rod endwise slidable in the axial bore of said rotary shaft and connected at one end to said sleeve and at its otherend to one of the elements of said feed-advance eccentric, a pivotally mounted yoke straddling said sleeve and connected thereto to permit rotation of said sleeve relative to said yoke, and manually turnable means connected to said yoke providing for swinging said yoke about its pivot.

4. A work-feeding mechanism for sewing machines having a rotary shaft formed with an axial bore, comprising a movable feed-dog, a feed-lift eccentric operatively connected to said feed-dog, an adjustable feed-advance eccentric mounted on said rotary shaft and operatively connected to said feed-dog and including relatively movable inner and outer elements having interengaging surfaces inclined to the longitudinal axis of said rotary shaft, a sleeve slidable on said rotary shaft, a. shift-rod endwise slidable in the axial bore'of said rotary shaft and connected at one end to said sleeve and at its other end to one of the elements of said feed-advance eccentric. a pivotally mounted yoke straddling said sleeve and connected thereto to permit rotation of said sleeve relative to said yoke, an eccentric operatively connected to said yoke, and means for turning said 'I5 456,235

eccentric to effect a swinging of said yoke about its pivot.

5. A work-feeding mechanism for sewing machines having a rotary shaft formed with an axial bore and alined slots, comprising a movable feeddog, a feed-lift eccentric operatively connected to said feed-dog, an adjustable feed-advance eccentric mounted on said rotary shaft and operatively connected to said feed-dog and includingk relatively movable inner and outer elements having interengaging surfaces inclined to the longitudinal axis of said rotary shaft, a sleeve slidable on said rotary shaft, a shift-rod endwise slidable in the axial bore of said rotary shaft, a diameter pin penetrating one end of said shift-rod and extending through said alined slots into the inner element of said feed-advance eccentric, a second diameter pin penetrating the other en-d of said shift-rod and extending through said alined slots into said sleeve, and connections for shifting said sleeve lengthwise of said shaft.

6. A work-feeding mechanism for sewing machines having a rotary shaft,` comprising a movable feed-dog, a feed-lift eccentric operatively connected to said feed-dog, an adjustable feed-V advance eccentric mounted on said rotary shaft and operatively connected to said feed-dog and including relatively movable inner and outer elements having interengaging surfaces inclined to the longitudinal axis of said rotary shaft, a sleeve slidable on said rotary shaft and formed with an annular groove, a connection between said sleeve and one of the elements of said feed-advance eccentric, a pivotally supported yoke straddling said 5' sleeve, a shoe disposed in said annular groove and fulcrumed on said yoke, an eccentric operatively connected to said yoke, and means for turning said eccentric to effect a swinging of said yoke about its pivot.

7. A work-feeding mechanism for sewing machines having a rotary shaft, comprising a movable feed-dog, feed-lift means operatively connected to said feed-dog, an adjustable feed-ad- Vance eccentric mounted on said rotary shaft and operatively connected to saidfeed-dog and including inner and outer elements having interengaging surfaces inclined to the longitudinal axis of said rotary shaft, and connections operative at will for positively shifting one of said elements relative to the other of said elements in a direction to vary the eccentricity of said feedadvance eccentric, said connections including a member shiftable along a line parallel to the longitudinal axis of said rotary shaft, a cam op- 5 eratively associated with said member, an-d man- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 267,124 Zelner Nov. 7, 1882 718,988 Dial et al Jan. 27, 1903 1,810,985 Reichenbach June 23. 1931 FOREIGN PATENTS Number Country Date 242,851 Germany Jan. 22, 1912 France June'13, 1913 

